Apparatus for supporting,heating and simultaneously illuminating a plurality of test tubes



Oct. 6, 1970 D. BOSER 3,532,435

APPARATUS FOR SUPPORTING. HEATING AND'SIMULTANEOUSLY1 nwmmmme A PLURALITY 0F TEST TUBES Filed July 27. 1966 v 2 Sheets-$heet 1 4 T TOR/V5 v.

Oct. 6, 1970 D. BOSER 3,532,435

APPARATUS FOR SUPPORTING, HEATING AND SIMULTANEOUSLY ILLUMINATING A PLURALITY OF TEST TUBES 1 Filed July 27, 1966' 2 Sheets-Sheet 2 INVENT0R 049W flow/L,

ATTORNEY.

United States Patent Office Patented Oct. 6, 1970 3,532,435 APPARATUS FOR SUPPORTING, HEATING AND SIMULTANEOUSLY ILLUMINATING A PLURAL- ITY OF TEST TUBES Dieter Boser, Zurich, Switzerland, assignor to Mettler Instrumente AG, Zurich, Switzerland, a corporation of Switzerland Filed July 27, 1966, Ser. No. 568,289 Claims priority, application Switzerland, Mar. 2, 1966, 2,979/ 66 Int. Cl. G01n N10 US. Cl. 356-246 4 Claims This invention relates to a measuring head for thermal analysis and more particularly to a measuring head having an oven body of thermoconductive material fitted with electric heating elements, in which the upper end face of the oven body is penetrated by a plurality of longitudinally extending nesting passages for receiving test tubes.

An object of the invention is a measuring head of the kind outlined, in which each of said nesting passages is intersected by an observation passage extending transversely to the axis of the respective nesting passage and terminating in the outer side face of said oven body, and in which the lower end face of said oven body is penetrated by a lighting passage terminating substantially at the centre of said oven body, said lighting passage incorporating means for the simultaneous illumination of the specimens to be analysed which are inserted in said test tubes. In an improved embodiment of such a measuring head at least some of said nesting passages may terminate in the end face of said lighting passage, each of these nesting passages being intersected by an observation passage at a location above from said end face. At least some other of said nesting passages have their bottom ends below the level of the upper end of said lighting passage, each of these other nesting passages being intersected by an observation passage which is disposed at.

such height in said oven body that they are continued equiaxially and terminate at the upper part of said light-' ing passage. The measuring head of the kind outlined may comprise in addition a light conductor of heatresistant glass, the top end face of which being of conical shape in order thereby to achieve an emergence of light in both an axial and radial direction, said light conductor being inserted in the lighting passage of the measuring head and virtually filling the same.

These and other objects and the advantages of the invention will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawing which shows, in simplified form, a measuring head for thermal analysis according to the invention.

FIG. 1 is a view of vertical cross section taken through the oven body of the measuring head, and

FIG. 2 is a plan view of the oven body shown in FIG. 1, the radially extending observation passages and the central lighting passage being shown in broken lines.

The oven body 3, consisting of copper or aluminum, is made as a solid block and is shaped like a circular cylinder having a vertical axis of rotation. Close to its outer cylindrical surface is inserted a heating coil 4 which extends helically over the entire height of the oven body. The latter is provided with a lighting passage 5 penetrating centrally from its bottom end face. The upper end face 6 of the lighting passage 5 is located approximately in the middle of the axial height of the oven body 3. Furthermore, starting from the top of the oven body, a plurality of nesting passages is provided, in groups, each of which is concentric with the axis of the oven 'body. The passages 7, 8 and 9 of larger cross section which are situated more closely to the axis of the oven body 3 open out into the lighting passage 5 directly at its top face 6. On the other hand, the nesting passages 10, 11 and 12 of the smaller cross section, which are somewhat more remote from the axis of the oven body 3, have their bottom ends below the level of the top end of the lighting passage 5 as shown in FIG. 1. Intersecting each of these nesting passages is a separate observation passage extending in a radial direction through the oven body 3 as far as its cylindrical outer face. The observation passages 13-, 14 and 15 associated with the inner nesting passages 7 to 9 extend from a zone above the top face 6 of the lighting passage 5, as is shown in FIG. 1. The observation passages 16, 17 and 18 which are associated with the outer nesting passages 10 to 12, on the other hand, are disposed at such a height in the oven body 3 that they are continued equiaxially and terminate at the upper part of the lighting passage 5 or at the conical end face 6 thereof. Inserted in the lighting passage 5 and virtually filling the same is a light conductor 19 of heatresistant glass. Its conical top face 20 achieves an emergence of light in both an axial and a radial direction. Finally, at a suitable place, the oven body 3 has yet a further passage 21 of small cross section which serves to accommodate a thermojunction 22 by means of which the temperature of the oven body can be measured.

A lamp 23 is provided in the measuring head, near the underside of the light conductor 19. Furthermore, opposite the outlet orifice of each of the observation passages 13 to 18, a photoelectric cell is provided. These photoelectric cells are denoted by the reference numerals 24 to 29 in the drawings. The lamp 23 and the photoelectric cells 24 to 29 are mounted on a jacket surrounding the oven body 3 and at a distance thereof, while the oven body 3 is likewise braced against the jacket in a heatinsulating manner. For reasons of clarity, however, the aforesaid jacket of the measuring head and the fixing means for holding the aforesaid measuring head components are not shown in the drawings.

According to the thermal analysis which is to be effected, test tubes 30 to 32 can be inserted into the passages 7 to 9. The specimens which they contain are illuminated from below and the initiation of any specific occurrence is observed by means of the scattered light emerging from the specimens and passing radially out through the observations passages 13 to 15. Observation in the scattered light is for example advantageously used for determining the boiling point of liquids.

Furthermore, with the measuring head described, it is possible to insert test tubes 33 to 35 in the outer nesting passages 10 to 12 and to observe the specimens contained therein in the light passing radially outwardly and through the said specimens. This has proved expedient for example in determining the melting point of the specimens. However, the case may also arise that a specific occurrence can only be observed with sufficient reliability by simultaneous observation of scattered light and permeating light. Under these conditions, the substance which is to be examined can for example be distributed over test tubes 30 and 35. The possibility of individual observation of the specimens located in each of the test tubes makes it possible, to carry out comparative, error or differential measurements easily, automation of thermal analysis being possible, if necessary, with the aid of the photoelectric cells.

:Since the nesting passages 7 to 12 and the observation passages 13 to 18 associated therewith have but a small cross section and are distributed in a regular manner within the oven body 3, a temperature gradient occurs only in the zones adjacent the top and bottom faces of the the same temperature prevails everywhere.

By reason of the advantages which have been described briefly hereinbefore, the measuring had is versatile in application. Apart from conventional absolute measurements of boiling and melting points, thermal analysis may be carried out in order to check the purity of substances, to identify specimens of substances, for determining molecular weight and for carrying out investigations to determine optical magnitudes of specimens of substances.

I claim:

1. A measuring head for thermal analysis comprising an oven body of thermoconductive material fitted with electric heating elements, in which the upper end face of said oven body is penetrated by a plurality of longitudinally extending nesting passages for receiving test tubes, in which each of said nesting passages is intersected by an observation passage extending transversely to the axis of the respective nesting passage and terminating in the outer surface of said oven body, and in which the lower end face of said oven body is penetrated by a lighting passage terminating at an end face substantially at the centre of said oven body, said lighting passage incorporating illuminating means for the simultaneous illumination of the specimens to be analyzed which are inserted in said test tubes.

2. The invention as recited in claim 1, wherein at least some of said nesting passages terminate in the terminating face of said lighting passage, each of these nesting passages being intersected by an observation passage at a location above said terminating face of said lighting passage.

3. The invention as recited in claim 1, wherein at least some of said nesting passages have their bottom ends below the level of the terminating face of said lighting passage, each of these nesting passages being intersected by an observation passage which is disposed at such a height in said oven body that they are continued equiaxially and terminate adjacent the terminating face of said lighting passage.

4. The invention as recited in claim 1, wherein said il luminating means comprise a light conductor of heatresistant glass, the top end face of said light conductor being of conical shape in order thereby to achieve an emergence of light in both axial and radial directions, said light conductor being inserted in said lighting passage and virtually filling the same.

References Cited UNITED STATES PATENTS 11/1964 Hufi 356-40 9/1966 Williams et al. 356-39 XR 

1. A MEASURING HEAD FOR THERMAL ANALYSIS COMPRISING AN OVEN BODY OF THERMOCONDUCTIVE MATERIAL FITTED WITH ELECTRIC HEATING ELEMENTS, IN WHICH THE UPPER END FACE OF SAID OVEN BODY IS PENETRATED BY A PLURALITY OF LONGITUDINALLY EXTENDING NESTING PASSAGES FOR RECEIVING TEST TUBES, IN WHICH EACH OF SAID NESTING PASSAGES IS INTERSECTED BY AN OBSERVATION PASSAGE EXTENDING TRANSVERSELY TO THE AXIS OF THE RESPECTIVE NESTING PASSAGE AND TERMINATING IN THE OUTER SURFACE OF SAID OVEN BODY, AND IN WHICH THE LOWER END FACE OF SAID OVEN BODY IS PENETRATED BY A LIGHTING PASSAID TERMINATING AT AN END FACE SUBSTANTIALLY AT THE CENTRE OF SAID OVEN BODY, SAID LIGHTING PASSAGE INCORPORATING ILLUMINATING MEANS FOR THE SIMULTANEOUS ILLUMINATION OF THE SPECIMENS TO BE ANALYZED WHICH ARE INSERTED IN SAID TEST TUBES. 